HO-1核转位调控NPM1/MDM2/p53/Arf：非酶活性依赖的血管内皮应激性衰老调节新机制

血红素加氧酶-1（HO-1）作为机体最重要的氧化应激防御酶而备受关注，但其非酶活性功能目前所知甚少，对心血管系统的调控作用尚不清楚。在血管内皮应激性衰老模型中，我们发现：HO-1出现明显核聚集；核内HO-1显著抑制内皮衰老，且该作用不依赖于酶活性；HO-1在核内通过与核仁磷酸蛋白NPM1相互作用，降低p53稳定性。据此我们提出假设：在内皮应激性衰老中，HO-1转位入核与NPM1结合，通过干扰胞核中NPM1/MDM2/p53/Arf相互作用，抑制p53、Arf等细胞周期抑制因子，发挥阻抑内皮衰老的保护作用。本项目拟采用基因工程小鼠、Crispr Cas9基因编辑等体内外实验手段，探究HO-1核转位在内皮衰老和血管稳态调节中的关键作用及调控机制，揭示HO-1抗氧化作用以外的新功能，以及其与酶依赖性内皮保护的协同作用及机制，为确立以HO-1为靶标干预血管老化、防治心血管疾病提供更充分的科学依据。

Heme oxygenase-1 (HO-1) serves as the most important endogenous enzyme against oxidative stress, and has attracted lots of attention for its heme-degraded enzymatic activity. However, it remains unclear whether HO-1 has non-enzymatic activity. And the exact regulatory role of its non-enzymatic activity in the cardiovascular system is under explored. In our previous observations, HO-1 was translocated into the nucleus in senescent vascular endothelial cells; nuclear HO-1 elicited anti-senescent effect independent of its enzymatic activity. Further observations demonstrated that nuclear HO-1 interacted with nucleophosmin (NPM1) to repress p53 stability. Based on these observations, a hypothesis was proposed: HO-1 translocated to the nucleus and interacted with NPM1 during endothelial senescence, interfering with NPM1/MDM2/p53/Arf interactions, inhibiting the cell-cycle repressors p53 and Arf, and subsequently protecting the endothelial cells against senescence. The present study will pave the way to illuminate the mechanisms underlying the regulation of nuclear HO-1 in endothelial senescence and vascular homeostasis, and will provide better understanding of the novel function of HO-1 besides its anti-oxidant effect, and the synergistic effect of its enzymatic and non-enzymatic activity in endothelial protection. This study will also provide solid evidence for HO-1 as a therapeutic strategy of vascular senescence and cardiovascular diseases.